Infrared nanospectroscopy and imaging of collective superfluid excitations in anisotropic superconductors

Stinson, H. T.; Wu, James Swi‐Bea; Jiang, Bor-Yuan; Fei, Zhe; Родин, Александр; Chapler, B. C.; McLeod, Alexander; Neto, Antonio Castro; Lee, Y. S.; Fogler, M. M.; Basov, D. N.

doi:10.1103/physrevb.90.014502

Cited by 39 publications

(49 citation statements)

References 58 publications

(103 reference statements)

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“…There are other types of polaritons, including Cooper‐pair polaritons, in‐plane anisotropic surface plasmon polaritons and hybrid polaritons like hyperbolic plasmon–phonon polaritons, which are worth further exploration. These polaritons also possess exotic optical properties and great potential in various applications.…”

Section: Discussionmentioning

confidence: 99%

Polariton Photonics Using Structured Metals and 2D Materials

Cai

Wang

et al. 2019

Advanced Optical Materials

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Polaritons are quasiparticles originating from strong interactions between photons and elementary excitations that could enable high tunability, tight electromagnetic field confinement, and large density of photonic states, making it possible to achieve novel and otherwise inaccessible functionalities. For these reasons, polaritons spawn great interest in the fields of physics, materials science, and optics for both fundamental studies as well as potential applications (e.g., modulators, photodetectors, photoluminescence, etc.). In recent years, the explosive growth of research in graphene and other 2D van der Waals materials is witnessed because they provide a new platform that substantially complements conventional metals, dielectrics, and semiconductors to investigate different polariton modes. This review highlights the works published in recent years on the topic of polariton photonics based on structured metals, graphene, and transition‐metal dichalcogenides (TMDs). The exotic optical properties of the polaritons in metallic structures and 2D van der Waals materials offer bright prospects for the development of high‐performance photonic and optoelectronic devices.

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Section: Discussionmentioning

confidence: 99%

Polariton Photonics Using Structured Metals and 2D Materials

Cai

Wang

et al. 2019

Advanced Optical Materials

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“…Such screening confines the field at the interface and forms surface polariton. Based on the types of the collective modes associated, polaritons can be classified into surface plasmon polaritons (SPPs), surface phonon polaritons (SPhPs), exciton polaritons (EPs), Cooper pair polaritons, and magnon polaritons, etc. Here we briefly introduce the first three, which have been successfully investigated in the ultrafast‐near field experiments.…”

Section: Origins and Classification Of Surface Polaritonsmentioning

confidence: 99%

Nanoimaging and Nanospectroscopy of Polaritons with Time Resolved s‐SNOM

Yao

et al. 2019

Advanced Optical Materials

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The development of electronics and photonics is entering a new era of ultrahigh speed sensing, data processing, and telecommunication. The carrier frequencies of the next‐generation electronic devices inevitably extend beyond radio frequencies, marching toward the nominally photonics‐dominated territories, e.g., terahertz and beyond. As a result, electronic and photonic techniques naturally merge and seek common ground. At the forefront of this technical trend is the field of polaritonics, where polaritons are half‐light, half‐matter quasiparticles that carry the properties of both “bare” photons and “bare” dipole‐carrying excitations. The Janus‐faced nature of polaritons renders the unique capability of operando control using photoexcitation or applied electric field. Here, state‐of‐the‐art ultrafast polaritonic phenomena probed by scattering‐type scanning near‐field optical microscope (s‐SNOM) techniques is reviewed. The ultrafast dynamical control and loss‐reduction of the polariton propagation are discussed with special emphasis on the creation and probing of the tip or edge induced plasmon– and phonon–polaritons in low‐dimensional systems. The detailed technical aspects of s‐SNOM and its possible future development are also presented.

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“…In summary, we proposed the concept of adiabatic amplification of collective modes in nonequilibrium systems under photoexcitation and suggested two possible routes for its experimental realization in 2D materials. Although we focused on systems with hot electrons, the concept of adiabatic amplification is also applicable to systems with "cold" electrons, for example, superconducting films [42,43], where plasmon damping can be even smaller than in graphene. This work is supported by the U.S. Department of Energy under Grant de-sc0012592.…”

Section: (C) Undermentioning

confidence: 99%

Adiabatic Amplification of Plasmons and Demons in 2D Systems

2016

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Semiclassical quantization rules and numerical calculations are applied to study polariton modes of materials whose permittivity tensor has principal values of opposite sign (so-called hyperbolic materials). The spectra of volume-and surface-confined polaritons are computed for spheroidal nanogranules of hexagonal boron nitride, a natural hyperbolic crystal. The field distribution created by polaritons excited by an external dipole source is predicted to exhibit raylike patterns due to classical periodic orbits. Near-field infrared imaging and Purcell-factor measurements are suggested to test these predictions. KEYWORDS:Hyperbolic materials, boron nitride, polariton, nanoresonator, Purcell's factor, semiclassical quantization R ecently much interest has been attracted to a class of uniaxial materials whose axial ε z and tangential ε ⊥ permittivities have opposite signs. These hyperbolic materials (HM) possess extraordinary rays with unusual properties. In this Letter, we focus on polar dielectric HM 1−5 where the extraordinary rays are phonon-polariton collective modes. Our results may also apply to other HM, including ferromagnets, 6 magnetized plasmas, 7 artificial metamaterials, 8 layered superconductors, 9,10 and liquid crystals. 11The basic properties of hyperbolic polaritons are as follows. Their isofrequency surfaces ω(p) = const in momentum space p = (p x , p y , p z ) are hyperboloids. In a broad range of |p| from the free-space photon momentum ω/c to an upper cutoff imposed by microscopic structure, these hyperboloids can be approximated by cones (Figure 1a)The group velocity v(p) = ∂ p ω is always orthogonal to the isofrequency surface. Hence, within the conical approximation it has a fixed angle α = tan/(ε z ) 1/2 ]} with respect to the optical axis. Such a strictly directional propagation of polaritons may be used for subdiffractional focusing 12,13 and super-resolution imaging known as "hyperlensing". 8,14−16Because the high-momenta polaritons remain immune to evanescent decay, volume-confinement of polaritons inside nanogranules 3,17,18 is possible. Several experimental observations of such modes in hexagonal boron nitride (hBN), a natural mid-infrared HM, have been reported. 2,3,12,13,17,19 (This layered insulator is also known to be a premier substrate 20 or a spacer for van der Waals heterostructures. 21,22 ) In the far-field spectroscopy, 3 the polariton modes of hBN nanogranules show up as discrete resonances. Remarkably, the spectrum of such resonances was found to depend primarily on the aspect ratio of the granules rather than their size or precise shape. Exact solutions 1,6,10 for spheroidal or spherical shapes enable one to compute such spectra but they do not elucidate the underlying physical picture.In this Letter, we further develop an alternative ray optics method 23 that makes connection to the Einstein−Brillouin− Keller (EBK) quantization 24,25 of a classical particle inside a cavity having the same shape as the granule. The indefinite permittivity tensor of the HM maps o...

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Infrared nanospectroscopy and imaging of collective superfluid excitations in anisotropic superconductors

Cited by 39 publications

References 58 publications

Polariton Photonics Using Structured Metals and 2D Materials

Polariton Photonics Using Structured Metals and 2D Materials

Nanoimaging and Nanospectroscopy of Polaritons with Time Resolved s‐SNOM

Adiabatic Amplification of Plasmons and Demons in 2D Systems

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